Full Idea
The question whether objective truth can be attributed to human thinking is not a question of theory but is a practical question; man must prove the truth of his thinking in practice.
Gist of Idea
Whether human thinking can be 'true' must be decided in practice, not theory
Source
Karl Marx (Theses on Feuerbach [1846], §II)
Book Reference
Marx,K./Engels,F.: 'The German Ideology', ed/tr. Arthur,C.J. [Lawrence and Wishart 1985], p.121
A Reaction
This would appear to be an assertion of the pragmatic view of truth well before Peirce. The obvious objections arise, such as whether falsehood (Plato's 'noble lie') might not have equal practical success, and whether truth might be disastrous.